Creature — Giant
* / *
Beanstalk Giant's power and toughness are each equal to the number of lands you control.
Sorcery — Adventure
Search your library for a basic land card, put it onto the battlefield, then shuffle. (Then exile this card. You may cast the creature later from exile.)
You must still follow any timing restrictions and permissions for the permanent spell you cast from exile. Normally, you'll be able to cast it only during your main phase while the stack is empty.